Injection blow molding processes and apparatus are widely known and widely used in industry. For example, reference should be had to U.S. Pat. No. 3,183,552 to Farkas, U.S. Pat. No. 3,819,314 to Marcus, U.S. Pat. No. 3,339,231 to Piotrowski and Canadian Pat. No. 995,418 to Cannon et al.
It is and has been a long standing objective of art processes to achieve a high productivity, i.e., to develop a process with a rapid, efficient and economical operating cycle. Art processes known heretofore are subject to one or more significant disadvantages. Frequently, they are cumbersome and expensive to operate. Frequently, they are characterized by a relatively slow operating cycle. A shorter operating cycle is particularly desirable since it is directly translatable into a larger number of end products produced.
Processes are known with overlapping cycles in order to reduce overall cycle time, for example, by providing that while one parison is being molded another is being blown and still another is being removed. However, even with processes using overlapping cycles the overall cycle time still leaves much to be desired and still necessitates improvement in cycle time.
The foregoing difficulties are further compounded by frequent lack of reliability of prior art processes necessitating frequent interruptions of the operation and thereby further impairing operating efficiency.
Accordingly, it is a principal object of the present invention to provide a process and apparatus for injection blow molding hollow plastic articles characterized by a rapid, efficient and economical operating cycle.
It is a still further object of the present invention to provide a process and apparatus as aforesaid which is convenient and easy to use on a commercial scale and may be reliably used with high productivity.
Further objects and advantages of the present invention will appear from the following specification.